One of the major objectives will be to develop a quantitative assay procedure for the growth factor (PGF) produced by plerocercoids of the tapeworm Spirometra mansonoides. Attempts will be made to obtain a dose response relationship between the dose level of PGF and one of the following known responses to PGF: increase in ornithine decarboxylase activity, increase in liver glycogen levels of PGF-treated hypophysectomized rats, stimulation of the epithelial mucosa of pigeon crop sacs, or stimulation of mouse fibroblast cells in culture. A second objective will be to isolate and identify PGF. There is preliminary evidence that PGF is a protein or polypeptide and a relatively clean band containing PGF activity has been obtained with disc gel electrophoresis. If PGF is a protein, various techniques will be employed to establish its purity. Once this has been accomplished, then the primary, secondary and tertiary structure of the protein will be determined. A third objective is to determine the mechanism by which PGF controls growth in rats, pigeon crop sacs, and certain cells in culture. The interrelationship of PGF to other growth factors such as somatotropin, prolactin, insulin, glucagon, thyroid hormone, somatomedin, and epidermal growth factor will be undertaken. The affects of PGF and the other hormones on various enzyme levels and metabolites will be studied in the hypox rat. A fourth objective is to determine whether PGF will stimulate growth in other mammals, especially primates and animals of potential commercial value.